The present invention relates to processes for hydroxylating olefins, preferably in the liquid phase, in the presence of a supported osmium catalyst, and a cocatalyst.
Processes for the production of glycols such as ethylene glycol, from olefins are well known in the art.
For example, it is well known from the technical literature and patents that olefins can be effectively oxidized to their corresponding vicinal diols with a strong oxidizing agent in the presence of catalytic amounts of specific osmium containing compounds, particularly osmium tetroxide.
The patent literature directed to osmium containing hydroxylation catalysts describes various osmium oxides used in homogeneous reaction systems in conjunction with specific oxidants. The primary oxide catalyst employed in these patents is OsO.sub.4, a highly volatile (B.P. 130.degree. C.) and toxic substance. Ordinarily, the toxic nature of OsO.sub.4 alone, while troublesome to some extent, could be dealt with by reasonably economic precautions. However, the combined properties of high volatility and toxicity (human tolerance is 0.002 mg/m.sup.3 of air) render this compound extremely dangerous necessitating large capital expenditures in plant safety equipment and design if one attempts to commercialize a process employing this compound as a catalyst for use in homogeneous reaction systems. It is for this reason that commercialization of OsO.sub.4 based plants has infrequently occurred in the past, if at all. If commercialization is attempted, the aforedescribed capital investment in safety equipment must reduce the profit margin on the products made by these processes.
Accordingly, it would be of extreme economic significance if alternative osmium catalysts could be identified which possess the property of low volatility and/or low toxicity (in relation to OsO.sub.4), together with processes for using the same to achieve glycol product selectivity and yield comparable to or better than the conventional OsO.sub.4 catalyst.
One important step in this direction is described in U.S. patent application Ser. No. 310,217, filed Oct. 9, 1981 of common assignee herein by R. Michaelson and R. Austin. This application discloses the use of various osmium halides and oxyhalides in the presence or absence of a wide variety of co-catalysts. However, these osmium containing catalysts are employed in a homogeneous reaction mixture. Consequently, these catalysts in commercial practice are circulated through the downstream processing steps which remove glycol products and any by-products. This leads to the use of costly equipment to recover the expensive osmium containing catalysts for recycle to the hydroxylation reactor. This disadvantage is inherent in all conventional processes for hydroxylating olefins using osmium containing catalysts since, to the best of applicants' knowledge, all of these processes employ unsupported homogeneous osmium catalysts to directly hydroxylate olefins thereby necessitating some type of catalyst recovery procedure.
The advantages of using a supported osmium catalyst in this area of catalysis are substantial, yet to date such use has not been disclosed in the prior art. For example, use of a supported catalyst permits the use of a fixed bed containing the supported osmium catalyst through which is passed the reaction mixture. Consequently, the osmium catalyst is contained in a localized area, thereby eliminating recovery and recycle equipment as well as the safety equipment needed to avoid contamination of the environment at the point where product is recovered. In addition, placing the osmium catalyst on a support would, in most instances, provide a means for facilitating the handling of the osmium catalyst and/or reduce its volatility, particularly where the osmium compound chemically reacts with the support.
Commonly assigned U.S. Pat. No. 4,314,088 and a continuation-in-part thereof, namely, U.S. patent application Ser. No. 310,099 filed Oct. 9, 1981 by R. Austin and R. Michaelson collectively, disclose the use of various halide containing co-catalysts in conjunction with osmium tetroxide catalyst and organohydroperoxide oxidants to hydroxylate olefins. The halide containing co-catalysts include alkali and alkaline earth metal halides hydrogenhalides, quaternary hydrocarbyl phosphonium halides, halogens, and transition metal halides. While it is disclosed generally in the aforenoted CIP application that the hydroxylation reaction can be conducted in a heterogeneous system, this application does not disclose a heterogeneous system containing a supported osmium catalyst.
U.S. patent application Ser. No. 310,097 filed Oct. 9, 1981 by R. Austin and R. Michaelson is directed to the hydroxylation of olefins using oxygen as an oxidant, a catalytically active metal oxide catalyst such as OsO.sub.4, and at least one transition metal salt co-catalyst. This application also discloses generally that the hydroxylation reaction can be conducted in a heterogeneous system but makes no reference to a heterogeneous system containing a supported osmium catalyst.
U.S. patent application Ser. No. 399,270 filed July 19, 1982, by R. Austin and R. Michaelson is directed to a process for hydroxylating olefins in the presence of an organohydroperoxide oxidant, as osmium containing catalyst and an organic halogenated hydrocarbon co-catalyst. The disclosure relating to supported osmium catalysts in this application as a source of osmium is derived from the process of the present invention.
Commonly assigned U.S. patent application Ser. No. 394,414, filed July 1, 1982 by Michaelson and Austin, is directed to the use of carboxylate salts as co-catalysts for use in conjunction with osmium oxides as a catalyst and organohydroperoxide as oxidant to hydroxylate olefins.
Various supported osmium compounds, have been reported in the literature and been the subject of considerable research as illustrated and described in the following publications: "Studies of Ethane Hydrogenolysis Over Group VIII Metals: Supported Osmium and Iron" by Sinfelt and Yates, J. of Catalysis, Vol. 10, p. 362-367 (1968); "Cyclopropane-Hydrogen Reaction Over the Group VIII Novel Metals" by Betta, Cusumano, and Sinfelt, J. of Catalysis, Vol. 19, p. 343-349 (1970); "Electron Microscopy Studies of Metal Clusters: Ru, Os, Ru-Cu, and Os-Cu" by Prestridge, Via, and Sinfelt, J. of Catalysis, Vol. 50, p. 115-123 (1977); "Extended X-ray Adsorption Fine Structure (EXAFS) of Dispersed Metal Catalysts" by Via and Sinfelt, J. of Chem. Phys. Vol. 71(2), p. 690-691 (July 1979); and "Co Hydrogenation Catalyzed by Magnesia-Supported Osmium Derived from Os.sub.3 (CO).sub.12 " by Deeba, Scott, Barth and Gates, J. of Catalysis, Vol. 71, p. 373-380 (1981). However, most existing supported osmium compounds have been employed under reducing conditions for hydrogenation catalysis and not for hydroxylation catalysis which occurs under oxidizing conditions.
U.S. Pat. No. 4,182,722 discloses a process for oxidizing acyclic and cyclic monoolefins with oxygen or oxygen containing gas using an ion-exchanged bimetallic solid catalyst to form epoxyalcohols. The bimetallic catalyst requires as exchanged ions at least one transition metal from Group V of the Periodic Table, such as vanadium, and at least one transition metal from Group IB or VIII, such as cobalt, copper, iron, rhodium, ruthenium, osmium, or iridium. Thus, the nature of the supported catalyst, the type of reaction which is catalyzed, and the oxidant employed all are different from that employed in the present invention.
None of the prior art which applicants' are aware disclose supported osmium catalysts for directly hydroxylating olefins to their corresponding diols. However, the following patents are discussed to provide a general background of the olefin hydroxylation prior art.
U.S. Pat. No. 2,414,385 discloses the use of hydrogen peroxide and a catalytically active oxide, such as osmium tetroxide, dissolved in an essentially anhydrous non-alkaline, inert, preferably organic, solvent, to convert, by oxidation, unsaturated organic compounds to useful oxygenated products such as glycols, phenols, aldehydes, ketones, quinones and organic acids. The formation of glycols is achieved by conducting the reaction at temperatures of between several degrees below 0.degree. C. and 21.degree. C. Such low reaction temperatures drastically, and disadvantageously, reduce the reaction rate to commercially unacceptable levels. At temperatures greater than 21.degree. C., the formation of aldehydes, ketones and acids is favored.
U.S. Pat. No. 2,773,101 discloses a method for recovering an osmium containing catalyst such as osmium tetroxide, by converting it to the non-volatile osmium dioxide form, distilling the hydroxylation product, reoxidizing the osmium dioxide to the volatile osmium tetroxide, and then recovering the same by distillation. Suitable oxidizing agents used to oxidize olfins, and reoxidize the osmium dioxide, include inorganic peroxides such as hydrogen peroxide, sodium peroxide, barium peroxide; organic peroxides, such as t-butyl peroxide or hydroperoxide, benzoyl peroxide; as well as other oxidizing agents such as oxygen, perchlorates, nitric acid, chlorine water and the like. As with other methods of the prior art, the above process yields undesirable by-products (see col. 1, line 55) thus reducing the selectivity of the process.
British patent specification No. 1,028,940 is directed to a process for regenerating osmium tetroxide from reduced osmium tetroxide by treatment of the latter with moleculr oxygen in an aqueous alkaline solution. More specifically, it is disclosed that when osmium tetroxide is used by itself as an oxidizing agent, or as a catalyst in conjunction with other oxidizing agents, to oxidize hydrocarbons the osmium tetroxide becomes reduced, and in its reduced form is less active than osmium tetroxide itself. Consequently, by conducting the oxidation reaction in the presence of an alkaline medium and supplying oxygen to the medium throughout the process, the osmium tetroxide is maintained in a high state of activity. The oxidation products disclosed include not only ethylene glycol from ethylene but also organic acids from such compounds as vicinal glycols, olefins, ketones and alcohols.
U.S. Pat. No. 4,255,596 is directed to a process for preparing ethylene glycol in a homogeneous single-phase reaction medium using ethylbenzene hydroperoxide as the oxidizing agent dissolved in ethylbenzene and osmium tetroxide as the catalyst. The pH of the reaction medium is maintained at about 14 by the presence of tetraalkyl ammonium hydroxide. A small amount of water can dissolve beneficially in the medium to reduce by-product formation and improve selectivity to the glycol.
U.S. Pat. No. 4,049,724 describes the preparation of glycols from alkenes and from unsaturated alcohols in an aqueous system using osmium tetroxide and specifying stable and water-soluble aliphatic hydroperoxides, such as t-butyl hydroperoxide, while a critical pH of 8 to 12 is maintained by a suitable combination of alkali metal buffering compounds. The preparation of propylene glycol utilizing t-butyl hydroperoxide is exemplified in the patent at a selectivity based on the hydroperoxide of 45%.
Japanese Patent Application No. Sho 54-145604, published Nov. 14, 1979 is directed to a process for hydroxylating olefins in the presence of OsO.sub.4, a quaternary ammonium salt such as tetraethyl ammonium bromide, and a peroxide including organoperoxides and H.sub.2 O.sub.2 as the oxidant.
U.S. Pat. No. 3,335,174 is directed to the use of water hydrolyzable Group Vb, VI-b and VII metal halides and oxyhalides (e.g., OsCl.sub.3) as hydroxylation and esterification catalysts in conjunction with aqueous H.sub.2 O.sub.2 as an oxidant. However, the process for using this catalyst requires the presence of lower aliphatic hydrocarbon acids such as glacial, formic, acetic and propionic acid as solvents. Under these conditions the reaction times vary from 1/2 to 4 hours, but at the shorter reaction times it is disclosed that substantial amounts of epoxide result. The only yield disclosed is obtained in connection with tungsten hexachloride in Example 1. This yield is extremely low, i.e., 22%, and includes both half-acetate and diol. Thus, among the major disadvantages of the process described in this patent are the low selectivities to diol and the corrosiveness of metal halides in the presence of glacial acids such as acetic acid.
See also: U.S. Pat. No. 3,317,592 (discloses production of acids and glycols using oxygen as oxidant, OsO.sub.4 as catalyst at pH 8 to 10); U.S. Pat. No. 3,488,394 (discloses hydroxylation of olefins by reacting olefin and hypochlorite in the presence of OsO.sub.4); U.S. Pat. No. 3,846,478 (discloses reaction of hypochlorite and olefin in an aqueous medium and in the presence of OsO.sub.4 catalyst to hydroxylate the olefin); U.S. Pat. No. 3,928,473 (discloses hydroxylation of olefins to glycols with O.sub.2 oxidant, octavalent osmium catalyst (e.g. OsO.sub.4), and borates as promoter); U.S. Pat. No. 3,931,342 (discloses a process for recovering glycols from an aqueous solution containing alkali metal borate and osmium compounds (e.g. OsO.sub.4); U.S. Pat. No. 3,953,305 (discloses use of OsO.sub.4 catalyst for hydroxylating olefins which is regenerated by oxidizing hexavalent osmium with hexavalent chromium and electrochemically regenerating hexavalent chromium); U.S. Pat. No. 4,203,926 (discloses ethylbenzene hydroperoxide as oxidant used in two-phase system to hydroxylate olefins in presence of OsO.sub.4 and cesium, rubidium and potassium hydroxides); U.S. Pat. No. 4,217,291 (discloses the oxidation of Osmium (III) or (IV) in an ionic complex with oxygen and an alkali metal, ammonium, or tetra (-lower) alkyl ammonium cation to a valency of greater than +5+organohydroperoxides); U.S. Pat. No. 4,229,601 (discloses the use of cesium, rubidium and potassium hydroxides as promoters for OsO.sub.4 catalyst and t-butyl hydroperoxide oxidant for hydroxylating olefins); and U.S. Pat. No. 4,280,924 (discloses a process for regenerating perosmate catalyst, e.g., cesium, rubidium and potassium perosmate).
Accordingly, there has been a continuing search for catalysts capable of improving processes for the hydroxylation of olefins. The present invention is a result of this search.